1. Field of the Invention
The present invention relates to a data processing system, and more particularly to such a system having a main memory which has a series of ports each for connection to a respectively independent processor unit, for example, a central processing unit and an input/output unit.
2. Description of the Prior Art
Such data processing systems are known for multiprocessor systems, for example, from "Elektronische Rechenanlagen" Vol. 11, No. 3, 1969, pp. 151-161 and Vol. 23, No. 3, 1981, pp. 107-115. It can occur, given such data processing systems, that the plurality of originally-provided ports of a main memory no longer suffices in the course of time in order, for example, to be able to connect even further input/output units as independent processor units. On the other hand, when addtional ports which are not initially required are provided, a considerable excess initial cost is involved.